Infrared Signature of the F135 engine?

All about the Pratt & Whitney F135 and the (cancelled) General Electric/Rolls-Royce F136
  • Author
  • Message
Offline

Corsair1963

Elite 3K

Elite 3K

  • Posts: 3751
  • Joined: 19 Dec 2005, 04:14

Unread post15 Dec 2015, 07:28

We now know the F-35 in fact has a lower RCS than the F-22. My question is that also true of the Infrared Signature?

I started to wonder after looking at the design of the F135's exhaust nozzle. Which, appeared far more complex than the one on the F119 from the Raptor. Then after reading more on the design. (based on F-16 LOAN Program) I see it has a number of features not found on the aforementioned. Which, includes things like special coating, internal cooling system, longer travel of hot exhaust gases, etc. etc.
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2140
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post15 Dec 2015, 08:33

IMO, IR signature is practically impossible to guess. There are features in F-35 and F135 that could make it very possibly have lower IR signature.

1. Higher bypass ratio means there is more cool air available to cool the engine and exhaust
2. Longer length meaning that hot parts of engine are further away from exhaust giving somewhat more time and space to cool the exhaust gases and even out the heat
3. Being developed directly from F119, it's likely there are lessons learned from it and improved in F135. This includes also IR signature.

IMO, F-35 very likely has lower IR signature flying subsonic due to these factors and F-22 very likely has lower IR signature supersonic due to supercruise ability.
Offline
User avatar

popcorn

Elite 3K

Elite 3K

  • Posts: 6892
  • Joined: 24 Sep 2008, 08:55

Unread post15 Dec 2015, 08:50

Also, 2 x F119 vs 1 x F135.
"When a fifth-generation fighter meets a fourth-generation fighter—the [latter] dies,”
CSAF Gen. Mark Welsh
Offline

Corsair1963

Elite 3K

Elite 3K

  • Posts: 3751
  • Joined: 19 Dec 2005, 04:14

Unread post15 Dec 2015, 09:11

Seems very logical.....still trying to find sources to support at least some of those conclusion.
Offline

charlielima223

Forum Veteran

Forum Veteran

  • Posts: 777
  • Joined: 12 Jan 2014, 19:26

Unread post15 Dec 2015, 09:54

interesting tid bit...

https://www.youtube.com/watch?v=FIKZjARXcos

this would lead me to believe that the different nozzle designs of BOTh F-22 and F-35 would have a slightly lower IR signature when compared to more conventional exhaust nozzles you see on other aircraft. Also at certain angles the engine nozzles of both Raptor and Lightning seem to be less visible.

Image

Image

Image

just me making a guess.
Offline
User avatar

Dragon029

Elite 1K

Elite 1K

  • Posts: 1077
  • Joined: 22 Dec 2014, 07:13

Unread post15 Dec 2015, 11:19

For the purpose of comparing nozzle diameters:

e0go7D1.jpg
Offline

hornetfinn

Elite 2K

Elite 2K

  • Posts: 2140
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post15 Dec 2015, 11:53

This is pretty good document about fighter aircraft infrared signatures:
http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA566304

Page 34 describes the main components of IR signature from different aspect angles:

Tail: Engine hot parts
2. Rear Quarter: Hot parts and exhaust plume
3. Beam to Forward Quarter: Airframe and exhaust plume
4. Nose: Airframe and intakes


F-35 and F-22 engines have both pretty well buried hot parts. For example F135 has unusually long exhaust pipe which narrows down the viewing angles where hot parts are visible. AFAIK, both have active cooling measures for airframe and exhaust nozzle and also exhaust gases. As seen in those pictures, both also have exhaust nozzle and also hottest part of exhaust gases well hidden behind tail components from most viewing angles. Of course all jet fighters can be easily seen by IR sensors from behind due to massive amount of heat generated by the engine. However the most important part is frontal and beam aspect angles. One important thing is solar reflections from canopy and airframe which are large contributors in IR signature of regular aircraft. Both F-22 and F-35 likely have very well suppressed solar reflections due to coatings used.

Here is also one interesting document about stealth features:
http://www.dror-aero.com/lectur/rcs3.pdf

I doubt you will find anything much more specific than those documents about signature reduction used in any specific aircraft.
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1386
  • Joined: 27 Mar 2015, 16:05

Unread post15 Dec 2015, 15:21

Another option is to dazzle or damage enemy's optical sensor by your LFR , the interesting part is imaging infrared sensor are easier to damage by laser compared to ancient conical reticle IR sensor
LRF.jpg

DIRCM effectiveness again EO sensor.jpg

power reqired to damage optic.jpg


https://books.google.co.uk/books?id=bBb ... &q&f=false
laser source.jpg

DIRCM (2).jpg

laser desinator Litening.jpg
Offline

Corsair1963

Elite 3K

Elite 3K

  • Posts: 3751
  • Joined: 19 Dec 2005, 04:14

Unread post16 Dec 2015, 11:03

Would TVC have any advantages in lowering the Infrared Signature???
Offline

eloise

Elite 1K

Elite 1K

  • Posts: 1386
  • Joined: 27 Mar 2015, 16:05

Unread post16 Dec 2015, 16:24

Corsair1963 wrote:Would TVC have any advantages in lowering the Infrared Signature???

No
Offline
User avatar

archeman

Forum Veteran

Forum Veteran

  • Posts: 685
  • Joined: 28 Dec 2011, 05:37
  • Location: CA

Unread post16 Dec 2015, 20:20

eloise wrote:
Corsair1963 wrote:Would TVC have any advantages in lowering the Infrared Signature???

No


Well...

It was an oversimple question and that probably prompted the oversimplified answer here.

There are widely different implementations of TVC, most have some effect on Infrared Signature. Some TVC solutions make the IR signature far greater than none at all.

Check out the X-31 'paddles' hanging out about 5' beyond the exhaust exit. An extreme example of exposing hot metal for all to view. (EDIT) Not metal really, "Made of carbon-carbon, the paddles could sustain temperatures of up to 1,500 degrees C for extended periods."

https://en.wikipedia.org/wiki/Rockwell- ... anding.JPG
Daddy why do we have to hide? Because we use VI son, and they use windows.
Offline

checksixx

Elite 1K

Elite 1K

  • Posts: 1525
  • Joined: 20 Jul 2005, 04:28
  • Location: Langley AFB, VA

Unread post17 Dec 2015, 01:36

Corsair1963 wrote:We now know the F-35 in fact has a lower RCS than the F-22.


Do we now?? LoL :roll:
Offline

Corsair1963

Elite 3K

Elite 3K

  • Posts: 3751
  • Joined: 19 Dec 2005, 04:14

Unread post17 Dec 2015, 06:26

checksixx wrote:
Corsair1963 wrote:We now know the F-35 in fact has a lower RCS than the F-22.


Do we now?? LoL :roll:



Are you saying you don't believe the F-35 has a lower RCS than an F-22???
Offline

charlielima223

Forum Veteran

Forum Veteran

  • Posts: 777
  • Joined: 12 Jan 2014, 19:26

Unread post17 Dec 2015, 13:41

Corsair1963 wrote:
Are you saying you don't believe the F-35 has a lower RCS than an F-22???


I remember when the USAF made the statement that the F-22 is has an RCS of metal marble and the F-35 of a metal golf ball. It was pretty much wildly accepted and somewhat debated. Most saying that those RCS figures were at their most optimum of angles (or something like that). Than skip a few years later and you have a USAF General saying that the F-35 is stealthier than the F-22 when before we were all lead to believe the F-22 is the "cream of the crop".

http://breakingdefense.com/2014/06/gen- ... -starts/3/

The F-35’s cross section is much smaller than the F-22’s, but that does not mean, Hostage concedes, that the F-35 is necessarily superior to the F-22 when we go to war

The F-35 is geared to go out and take down the surface targets,” says Hostage, leaning forward. “The F-35 doesn’t have the altitude, doesn’t have the speed [of the F-22], but it can beat the F-22 in stealth.” But stealth — the ability to elude or greatly complicate an enemy’s ability to find and destroy an aircraft using a combination of design, tactics and technology — is not a magic pill, Hostage reminds us.


IMO this makes me think that the F-35 at multiple angles (not just at the most optimal) has the lower overall RCS. Of course the Gen. Hostage does mention design, tactics, and technology. This makes me think again that with the F-35's more comprehensive sensor fusion and wider array of sensors; the F-35 has a better time at staying undetected longer than the F-22 can. Essentially it can see and know more. My own opinion on how I understand and interpret what the General said of course.
Offline
User avatar

sferrin

Elite 3K

Elite 3K

  • Posts: 4295
  • Joined: 22 Jul 2005, 03:23

Unread post17 Dec 2015, 14:02

checksixx wrote:
Corsair1963 wrote:We now know the F-35 in fact has a lower RCS than the F-22.


Do we now?? LoL :roll:


'cuz you know more than the General right? LoL :roll: This from the same guy who nearly burst a blood vessel in denial about radar blockers in the exhaust on the F-22. :lmao:

"The F-35’s cross section is much smaller than the F-22’s, but that does not mean, Hostage concedes, that the F-35 is necessarily superior to the F-22 when we go to war

The F-35 is geared to go out and take down the surface targets,” says Hostage, leaning forward. “The F-35 doesn’t have the altitude, doesn’t have the speed [of the F-22], but it can beat the F-22 in stealth.” But stealth — the ability to elude or greatly complicate an enemy’s ability to find and destroy an aircraft using a combination of design, tactics and technology — is not a magic pill, Hostage reminds us."
"There I was. . ."
Next

Return to F-35 Engine

Who is online

Users browsing this forum: ricnunes and 1 guest